Internal combustion engine



Aug. 6, 1935. A. P. BRUSH 2,010,056

' INTERNAL COMBUSTION ENGINE Filed NOV. 6, 1935 6a 7 AM/ 46 30 INVENTORL v filazrsorz F. ,Bras/y.

ATTORNEY5.

Patented Aug. 6, 1935 UNITED STATES PATENT OFFICE INTERNAL COMBUSTION ENGINE Alanson P. Brush, Detroit, Mich.

Application November 6, 1933, Serial No. 696,759 2 Claims. (01. 74-24210) This invention relates to internal combustion engines and particularly to those having a chain belt drive between different parts thereof, and is particularly applicable to internal combustion engines of the overhead cam shaft type employing a single chain belt as a driving means between the cam shaft and the crank shaft.

Objects of the invention include a novel means for taking up the slack developing in a chain belt because of wear; to provide such means in which the slack of a chain belt may be taken up without substantial change in the timed relation between the driving and driven elements connected thereby; to provide means for simultaneously taking up the slack in both sides of a chain belt; and to provide a novel construction whereby the chain belt connecting the crank shaft and cam shaft of an overhead valve type of internal combustion engine may be taken up in order to offset wear occurring in the chain belt in such a manner that the desired timed relation between the cam shaft and the crank shaft is not disturbed in taking up such wear.

The above being among the objects of the present invention, the same consists in certain novel features of construction and combinations of parts to be hereinafter described with reference to the accompanying drawing, and then claimed, having the above and other objects in In the accompanying drawing which illustrates one suitable embodiment of the present invention and in which like numerals refer to like parts throughout the several different views,

Fig. l is a front elevational view of an internal combustion engine of the overhead valve type, the chain or chain belt housing at the front end thereof being broken away to disclose the mechanism normally enclosed thereby, and certain other parts being broken away or shown in section in order to better illustrate the construction.

Fig. 2 is a fragmentary vertical sectional view of the front endof the engine shown in Fig. 1, taken on the line 2-2 thereof.

Fig. 3 is an enlarged, fragmentary, partially broken sectional view taken on the line 3-3 of Fig. 1.

M Fig. 4 is an enlarged sectional view taken longitudinally through a portion of the chain belt shown employed in the previous views, ina plane perpendicular to the pivot pins thereof.

As is well understood in the art, it is conventional practice to drive the cam shaft of an internal combustion engine from the crank shaft thereof by either gears or chain belts. Chain belts are normally preferred because of their more silent operation, smaller cost, and capability of being taken up to compensate for wear occurring therein. In the past where chain belts have been employed between the cam shaft and crank shaft of overhead valve types of internal combustion engines having the cam shaft disposed in the head of the engine adjacent the valves, it has been customary to provide two 10 chain belts arranged in series with each other; this having been necessitated for two reasons. The first of these reasons is that in such types of engines a relatively great distance separates the crank shaft from the cam shaft and were the 5 conventional method, consisting of an idler pulley or its equivalent engageable with one side only of the chain belt employed, the amount which the idler pulley would have to be capable of moving in order to take up a reasonable amount of 2 wear in the chain belt would be difficult of attainment without resulting in an unusually bulky structure which would be both unsightly and in many cases result in materially increasing the effective lateral dimensions of the engine. 25 The other reason is that where one idler pulley or its equivalent is employed, as in conventional constructions, the relatively great amount of wear in such a long chain belt when taken up on one side only thereof would act to advance the 30 crank shaft in its rotation relative to the cam shaft and thus have the effect of retarding the desired point of operation of the valves.

By using two chain belts in series as has been conventional in the particular type of engine under discussion, and taking up the wear in such belts by adjusting the intermediate pulleys or sprockets in a direction transverse to a line connecting the cam shaft and the crank shaft, it has had the effect of taking up both sides of 4 the belt simultaneously, thus resulting in a minimum amount of adjusting movement of the intermediate sprockets in order to take up the wear in the chain belts and has maintained the proper timed driving relation between the cam shaft and the'crank shaft regardless of such adjustment. The means provided by the present invention includes all of the advantages of the series type of chain belt drive above described and, at the same time, eliminates the disadvantage of having a plurality of chain belts in series, the greater relative-cost of the series drive, and permits a reduction in the overall length of the engine by an amount equal to the width of one of the chain belts.

Referring now to the drawing, an internal combustion engine is indicated as having an integral crank case and cylinder block if! and a cylinder head l2. In the present instance the engii e shown as by way of illustration includes a front plate is suitably secured to the forward end face of the cylinder block W and lower portion of the cylinder head 52, and through which the forward end of the crank shaft l8 projects. The cylinder head 52 rotatably supports the cam shaft l8 which cooperates with rocker arms 29 to operate the intake and exhaust valves 22. The crank shaft l6 immediately forwardly of the front plate M is provided with a sprocket 24 and in vertical alignment therewith the cam shaft i8 is provided with a similar sprocket 26, the sprocket 2% being twice the diameter of the sprocket 24 and hence having doubled the number of teeth so as to rotate the cam shaft at half the speed of the crank shaft in accordance with conventional'practice in connection with four cycle engines. A chain belt 23 of conventional construc tion is looped around the sprockets 24 and. 26 so as to drivingly connect one to the other. A chain housing 39 of conventional construction is secured to the front plate M over the pulleys 2 3 and 26 and their cooperating chain 28 in a manner well known to those skilled in the art.

In order to take up wear of the chain belt 28 ,two additional pulleys or sprockets 32 and 34 moving both of the pulleys 32 and 34 simultaneously in the same direction, thereby to take up any wear or slack in the chain belt 28 and, as will be apparent, where both of these pulleys are moved simultaneously both sides of the chain belt are taken up simultaneously so that the operation of taking up the wear or slack in the chain belt will not change the timed relation of the sprockets 24 and 2B, and parts associated therewith. In taking up the slack or wear on both sides of the chain belt 28 upon equal movement of the pulleys 32 and 34, a difference in the angular relation between opposite end portions of the chain belt on opposite sides of the sprockets 2d and 26 will develop upon adjustment for wear, resulting in a difference in amount of takeup on such opposite sides during adjustment, but this difference may be substantially offset by positioning the smaller pulley 32 in such a manner that the cooperating side of the chain belt on either side thereof is disposed at a more acute angle over it than that over the larger pulley 34,

In the present case the pulley 32 is shown of the same diameter as the sprocket 24 and in the form of a sprocket for the reason that the pulley 32 is adapted to drive the accessory drive shaft 36 for the electric generator (not shown) and/or other usual devices, and the pulley 3 is made of a larger diameter than the pulley 32 for the reason that it is thereby subjected to less wear during operation. Where, as in the case illustrated, one of the pulleys 32 or 34 is employed for driving accessories of the engine, it is formed as a sprocket as shown and is provided with gear teeth for driving engagement with the chain belt 28 so as to be driven therefrom. In the case of the pulley 3 3, however, which in the case indicated is employed simplyas an idler adjustment pulley, it may be made perfectly smooth. I find it desirable, in order to reduce the wear of both the pulley 34 and the chain belt 28, to form the pulley 34 as a sprocket as shown for inter-engagement with the chain belt 28 in the same manner as the pulley 32. Where such is the case it will be apparent that the chain belt 28 is so arranged that its outer surface passes over the pulley S 5 and, accordingly, the chain belt 28 in such case must be of the so-called back laced type, that is, of the type illustrated in greater detail in in which the alternate links of the belt are reversed one from the other so as to be capable of driving from either face thereof. This type of belt is conventional and, as will be apparent, is reversible.

The means for supporting the pulleys 232 and 36 for simultaneous adjustment across the end face of the engine is as follows. A bracket member 43, having a flat rear face adapted to lie in contact with the forward face of the front plate M, is provided at opposite ends thereof with forwardly projecting integral tubular bosses or sleeves 42 and i l. The pulley 3 is internally hushed and rotatably received upon the sleeve 42. A cup member 46 is axially, slidably received within the sleeve 52 and its outwardly flared rim projects radially outwardly into overlapping relation with respect to the hub of the pulley 34. A second cup 48, reversed in position to the cup 46, and a coil spring 50 is received within and maintained under constant compression between the bottoms of the cups A5 and id, the cup 38 being pressed outwardly against the inner face of the chain housing or cover 35 and the radially projecting flange of the cup member 45 abutting against the forward end of the sleeve is and providing an abutment for the pulley B l in order to maintain it against axial displacement as well as to urge this end of the bracket til against the front plate 14.

The sleeve 44 is internally provided with a bushing element 52 which projects rearwardly therebeyond through a transversely elongated slot 54 in the front plate It where it is guided for movement transversely of the engine. The forward end of the bushing 52 is outwardly flanged so as to prevent axial displacement of the bushing 52 rearwardly relative to the sleeve 44 and its rearwardly projecting end is threaded for cooperation with a nut 56. Between the nut 56 and the rear face of the front plate M is a relatively large collar or washer 58 which is provided for the purpose of sealing the slot 54 against the escape of lubricant therethrough. Additionally, a suitable sealing element indicated generally as at 623 and which may be of any suitable construction is preferably associated with a nut 56 for the purpose of preventing leakage of lubricant from the chain housing along the accessory drive shaft 36 which is rotatably received within the bushing 52 and which is suitably connected at its forward end with the pulley 32 for driving movement therefrom.

Adjacent the pulley 34 the bracket 40 is preferably provided with a horizontally extending slot 64 therein, as best illustrated in Figs. l and 3, and a pin 66 is slidably received in the slot 54 and is threadedin the front plate Ml so as to guide the bracket 40 in its adjusting movement. In the particular case shown the pin 66 is shown as of the headed type although it will be apparent that this is unnecessary in view of the fact that the spring 5!) acts through the cups 4% and as to con stantly maintain this end of the bracket 40 in contact with the forward face of the front plate I 4.

The right hand end of the bracket 40 as viewed in Figs. 1 and 3 is provided with a forwardly projecting lug 68. A screw Ill is threaded through the adjacent side of the chain housing 30 in alignment with the lug 6B and is adapted to contact therewith. The inner end of this screw, if desired, may be reduced as at 12 and be received in a cooperating opening in the lug 68. A look nut 14 may be provided on the screw ID for looking the screw 10 in adjusted position.

With the above described construction, when it is desired to take up any wear or slack in the chain belt 28, the nut 56 is loosened, thus unclamping the bracket 40 from the front plate I4, the lock nut 14 is backed off, and the screw 10 is threaded inwardly, thus causing the bracket 40 together with the pulleys 3'2 and 34 to move as a unit to the left, as viewed in Figs. 1 and 3, until the desired tension on the chain 28 is provided. After the bracket 40 and pulleys 32 and 34 have been moved the desired degree, the lock nut 14 may again be tightened up and the nut 56 tightened to again clamp the bracket 40 to the front plate l4. It will be observed that in this adjusting movement the left hand end of the bracket 40, as viewed in Fig. 1 is caused. to move in a horizontal direction because of the bushing 52 being guided in the slot 54, and likewise the upper end of the bracket 43 is caused to move in the same direction by reason of the pin 66 arranged in guiding relation to the slot 64.

It is to be understood that the above described construction illustrates merely one form which the present invention may assume and that it is subject to various modifications and changes without departing from the spirit and substance of the broad invention, the scope of which is commensurate with the appended claims.

What I claim is:

1. In combination with a pair of spaced rotatable elements, a sprocket secured to each of said elements, a chain belt trained over said sprockets, a third sprocket intermediate the first two mentioned sprockets in driven engagement with said chain belt, a pulley disposed between said first two mentioned sprockets and engageable with said chain belt on the side thereof opposite to that engaged by said third sprocket, the diameter of said third sprocket being smaller than the diameter of said pulley and said third sprocket being so positioned relative to the adjacent side of said belt that the angularity of the parts of said chain belt on opposite sides thereof is less than the angularity of the corresponding parts of said chain belt in engagement with said pulley, and means for simultaneously shifting said third sprocket and said pulley relative to said first two mentioned sprockets.

2. In an internal combustion engine, in combination, a crank shaft, a cylinder head, valves carried by said cylinder head, a cam shaft rotatably supported by said cylinder head, means operatively connecting said cam shaft with said valves, an accessory drive shaft extending along the side of said engine in generally parallel relation with respect to the axis of said crank shaft between said crank shaft and cam shaft, a sprocket fixed to said crank shaft, a sprocket fixed to said cam shaft, a sprocket fixed to said accessory drive shaft, a single belt chain trained over and enclosing all of said sprockets, a bracket member supported by said engine for bodily shiftable movement in a direction transverse to a line joining said crank shaft and said cam shaft, means disposed on the exterior of said engine for effecting bodily shiftable movement of said bracket, said sprocket on said accessory drive shaft being rotatably supported by said bracket for bodily shiftable movement therewith, and a pulley rotatably supported by and bodily shiftable with said bracket engaging the outer face of said belt chain on the side thereof, with respect to a line joining said crank shaft and said cam shaft, opposite to that engaged by said sprocket on said accessory drive shaft.

ALANSON P. BRUSH. 

